Yet after recovering the previous two days, the major banks again weakened to build on May's sharp losses as uncertainty has grown over a new tax on the liabilities of the biggest lenders and regulatory capital requirements.

Big mining stocks retreated with a further decline in Chinese steel and coal commodities, with iron ore down sharply after slumping 15% over the last five sessions.

A 3.1% fall by conglomerate Wesfarmers also weighed on the wider market, after Morgan Stanley lowered its stance on the stock and warned investors were underestimating the hit Wesfarmers' retail operations could take with Amazon's coming arrival in the country.

Westpac Banking and National Australia Bank each lost 0.7%, Australia & New Zealand Banking fell 0.2% and Commonwealth Bank of Australia slipped into the red.

Among mining stocks, BHP Billiton and Rio Tinto were 0.7% and 1.7% lower, respectively, and Fortescue Metals Group was 3.7% weaker.